Catalytic Pyrolysis of Polystyrene over Steel Slag under CO 2 Environment.

As the consumption of plastic materials has been dramatically increased, the abundant presence of their debris has become a significant problem worldwide. Thus, this study proposes a sustainable plastic conversion platform for energy recovery. In detail, polystyrene pyrolysis was examined as a case study under CO ₂ atmosphere in reference to N ₂ condition. The major gaseous and liquid products from polystyrene pyrolysis include permanent gases (syngas and C _1-2 hydrocarbons) and condensable aromatic compounds. Under CO ₂ environment, the reduction of polycyclic aromatic hydrocarbons (PAHs) was achieved during polystyrene pyrolysis, in comparison with N ₂ condition. Since its slow reaction kinetics, conversion of condensable hydrocarbons into permanent gases was not fully activated. Therefore, a cheap industrial waste, steel slag (SS), was employed as a catalyst to increase reaction kinetics. The synergistic effects of SS and CO ₂ contributed to doubling H ₂ production, while CO formation increased more than 300 times, in reference to non-catalytic pyrolysis. Because CO ₂ acted as an oxidant for CO production, control of H ₂ /CO ratio was achieved in different conditions. Thus, the utilization of CO ₂ would suggest a promising way to reduce the formation of PAHs, adopting the reliable platform to produce syngas from plastic waste.
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